240 young adolescents with Type 1 diabetes (DM1) will be studied in a three year prospective study that will include a comprehensive assessment of family and adolescent behavioral predictors and mediators of self- management, adherence to treatment, and DM1-related morbidity. The proposed study has the following specific aims: 1) to assess individual differences in patterns of self-management and adherence of DM1 from early to middle adolescence;2) identify family and adolescent behavioral influences on change in self- management and adherence;and 3) to document the consequences of self-management and adherence on blood sugar control, hyperglycemic episodes, and health care utilization. In order to accomplish these aims, a model of family and adolescent influences on self-management and adherence will be tested using data analytic methods that characterize individual trajectories of self-management over time. The following hypotheses will be tested: 1) quality of family communication and family support of diabetes management and autonomy will influence adolescents'behavioral autonomy and autonomy with respect to DM1 self- management and adherence;2) adolescents who demonstrate adaptive behavioral and diabetes-related autonomy and who are supported in their diabetes management by their parents will be more likely to develop effective, autonomous self-management and adherence;3) adaptive self-management and adherence to DM1 treatment will enhance blood sugar control, reduce frequency of hypoglycemia, and health care utilization. The proposed study will generate important, clinically relevant scientific data concerning the causes and consequences of self-management of DM1 diabetes during early adolescence. Information from the proposed study will facilitate the development of preventive interventions to address problem patterns of DM1 self-management among young adolescents in order to lessen the deterioration in DM1-related treatment adherence and glycemic control that often occurs during adolescence. The development of targeted interventions based on data from the proposed study will have public health significance for enhancement of blood sugar control and reduction of DM1 related morbidity in adolescents and young adults.